Chapter 2.4: 3-D Topo Surface Visualization of Metal Multiligand Systems: Quantification of Complexation in Unseparated Ligand Mixtures. Part 1 – 1:1 Complexes

Authors

• Garon C. Smith, University of Montana, MissoulaFollow
• Md Mainul Hossain, North South University, Bangladesh
• Patrick MacCarthy, Colorado School of Mines

Files

Description

This chapter describes systems in which a mixture of ligands is present. This is a handy concept to explore considering that geochemical and biochemical solutions often contain mixtures of ligands that are not easily separated. Instead of characterizing the complexation between ligands and metal ions with a stability constant, a stability function is introduced. The values for the function will land between that of the strongest complex’s stability constant and that of the weakest complex’s stability constant. The function’s value is a weighted average of the individual constants of the components present with the weighting factors being the relative abundance of each free species at a particular grid point. Interestingly, under certain conditions, a mixture of ligands behaves as if it were a single “hybrid” ligand. Whenever this happens, the stability function surfaces will show flat regions.  Under significant excess free ligand conditions, a high plateau is seen, the so-called CLASP-u (conditional limiting average stability product). Under significant excess metal conditions, a lower CLASP-l plain is observed. Intermediate CLASP-i’s emerge when intermediate strength complexes temporarily dominate for some compositions. Two different styles of grids are used to examine the behavior of ligand mixtures. Systab TOPOS and Multiligand TOPOS are downloadable Excel workbooks in supplemental files that allow readers to simulate this behavior for many metal-multiligand systems. A PowerPoint lecture and teaching materials are also provided, suitable for inclusion in upper division and graduate courses in analytical chemistry, biochemistry and geochemistry.

Publication Date

5-2026

Document Type

Book

Rights

© 2021 Garon C. Smith, Md Mainul Hossain, Patrick MacCarthy

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Disciplines

Chemistry

Recommended Citation

Smith, Garon C.; Hossain, Md Mainul; and MacCarthy, Patrick, "Chapter 2.4: 3-D Topo Surface Visualization of Metal Multiligand Systems: Quantification of Complexation in Unseparated Ligand Mixtures. Part 1 – 1:1 Complexes" (2026). Water Topos: A 3-D Trend Surface Approach to Viewing and Teaching Aqueous Equilibrium Chemistry. 11.
https://scholarworks.umt.edu/topos/11